We have built a GUI-based tool named RetroRank as described in Figure REF . RetroRank takes as an input a user query (such as a set of keywords extracted from title and/or long description of bug report). As an output, RetroRank returns a ranked list of bug-fixing comments extracted from cross-cutting discussion threads from past resolved bug. RetroRank relies on MySQL database where it stores all OSS bug reports and OSS repositories. The UI platform is built upon well-known Python packages: i) tkinter that is a standard GUI package to build the framework and ii) sklearn used to build functionalities of RetroRank. In practice, RetroRank is designed to adapt to any commercial or OSS project that support modern development practices. The inclusion of `pre-merge' code review [1]}, [2]} is an example where relevant comments can be used as part of code review [3]}, [4]}. Currently, RetroRank supports four OSS projects (i.e., GCC Compiler, Eclipse IDE, LibreOffice, and Apache Server). A screenshot in Figure REF  shows a list of recommended bug-fixing comments that can be used to address bug #61852. In this example, the RetroRank recommended several past fixed bugs (i.e., #26494, #40989, #53063, and #52304) and their associated bug-fixing comments shown in column 8;
